# Geostationary Environment Monitoring Spectrometer (GEMS)
*sensor . products*

Geostationary atmospheric-composition spectrometer flown on GEO-KOMPSAT-2B.

## Specifications
- **manufacturer**: ball-aerospace
- **product status**: operational
- **deployment context**: orbital
- **sensor**: {"instrument_family":"passive-optical","measurement_principle":"passive","spec_disclosure":"undisclosed"}
- **entity type**: sensor
- **last verified date**: 2026-06-16
- **verified by**: agency-doc
- **claim status**: agency-sourced
- **provider**: ball-aerospace
- **attributes**: {"kind":"sensor","manufacturer":"ball-aerospace","product_status":"operational","deployment_context":"orbital","description":"Geostationary atmospheric-composition spectrometer flown on GEO-KOMPSAT-2B.","sensor":"{\"instrument_family\":\"passive-optical\",\"measurement_principle\":\"passive\",\"spec_disclosure\":\"undisclosed\"}"}

## Editorial
Geostationary Environment Monitoring Spectrometer (GEMS) is an operational geostationary UV-visible hyperspectrometer on GEO-KOMPSAT-2B, launched in February 2020.[^nier-gems-intro][^wmo-gems] It measures sulfur dioxide, nitrogen dioxide, ozone, formaldehyde, and aerosols over East and Southeast Asia from geostationary orbit.[^nier-gems-intro] Its documented instrument class is a UV/VIS grating imaging spectrometer with a 300-500 nm range, spectral resolution below 0.6 nm, hourly daylight coverage over 5 S to 45 N and 75 E to 145 E, and 5 km resolution over Korea.[^wmo-gems]

Tropospheric nitrogen dioxide and sulfur dioxide column retrieval is demonstrated on GEO-KOMPSAT-2B.[^nier-gems-intro] Peer-reviewed validation work documents GEMS polarization characteristics and a correction algorithm, which matters for users evaluating radiometric stability and trace-gas retrieval quality in the UV-visible range.[^gems-polarization-amt-2024] GEMS supports regional air-quality and atmospheric-composition monitoring that needs frequent daylight geostationary refresh over Asia rather than global polar-orbit coverage.[^nier-gems-intro][^wmo-gems]

## Compositional position
- geo-kompsat-2b (missions) --[mission_payloads]--> Geostationary Environment Monitoring Spectrometer (GEMS)

## Sources
- [nier-gems-intro] | Introduction to GEMS onboard GK-2B | https://nesc.nier.go.kr/en/html/cntnts/73/satellite/introduction.do | tier=agency-doc | accessed=2026-06-16
- [wmo-gems] | WMO OSCAR instrument record: GEMS | https://space.oscar.wmo.int/instruments/view/gems | tier=agency-doc | accessed=2026-06-16
- [gems-polarization-amt-2024] | Geostationary Environment Monitoring Spectrometer (GEMS) polarization characteristics and correction algorithm | https://amt.copernicus.org/articles/17/145/2024/ | tier=peer-reviewed | accessed=2026-06-16
- [bae-gems-factsheet] | GEMS factsheet | https://www.baesystems.com/dam/jcr%3A32ac8a6c-e27d-45d8-a287-a43148383b15 | tier=operator-datasheet | accessed=2026-06-16

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Source: https://eo-atlas.org/products/sensor/gems
Maintainer: SpectraWorks B.V. (CC-BY 4.0)